At present, for a small and thin backlight module, light emitting diodes (LEDs) are often used for lighting, wherein a light guide plate is indispensable for the backlight module.
In normal, the light guide plate has scattering patterns or microstructures. In comparison with the scattering patterns, steps and a transport cost for processing the scattering patterns are omitted with the use of the microstructures, thereby saving manufacturing cost, as well as raising a production speed of devices.
However, the light guide plate with the microstructures has the defects described as follow. For visual effects, a desirable light guide plate has a higher brightness at a middle position thereof and a lower brightness at the fringe thereof. Referring to FIG. 1, a structural diagram showing a conventional light guide plate is illustrated. Regarding a light along a direction y, a distribution of the light along the direction y can be improved by adjusting an arrangement of the microstructures 111, so to adjust a uniformity of a panel brightness. Regarding a light along a direction x, the microstructures 111 are elongated microstructures with the same profile extending along the direction x, Thus, a distribution of the light along the direction x can not be improved by the microstructures 111, reducing a utilization rate of the light. Referring to FIG. 1 again, the brightness of the light along the direction y is detected at two positions A and B along the direction x, respectively. When an average brightness at the position A is defined as 100%, an average brightness at the position B is detected as 98%. In contrast, an average brightness at a side position of a light guide plate with the scattering patterns is detected as 92%. That is, in the direction x, the light guide plate can not concentrate the light on the middle position efficiently, and a portion of the light of a light source is distributed to both sides of the light guide plate. Accordingly, the brightness at the middle position can not be enhanced resulting in a loss of the light energy. In addition, the conventional light guide plate can not alter the light distribution thereof according to a user's requirements.
As a result, it is necessary to provide a light guide plate and a backlight module to solve the problems existing in the conventional technologies, as described above.